Current spacecraft technology provides all the resources for a spacecraft in the portion of the spacecraft known as the “bus” (sometimes also referred to as “spacecraft bus”). The bus is usually a very large portion of the spacecraft and contains power, propulsion, communication, control functions, data acquisition, solar arrays and antennas necessary to perform the various tasks that the spacecraft will be required to perform once placed in orbit. However, many smaller emerging spacecraft require hours or days of operation, and not years, as with typical spacecraft of past years. New emerging spacecraft also require less battery power and often times do not require solar arrays. Such small and emerging spacecraft may involve antennas, re-entry structures, propulsion devices, imaging devices, weather devices or sensors, radiation and environmental devices or sensors, and communication devices or sensors. Furthermore, many such emerging spacecraft that form non-primary payloads that one desires to place in orbit simply require space access and not specific orbits or inclinations, thus resulting in no need for an on-board propulsion subsystem for the non-primary payload.
Emerging spacecraft often do not need all of the capabilities of a traditional spacecraft bus that is otherwise required for a traditional spacecraft to achieve orbital status. Presently, spacecraft buses are developed with standard capabilities in particular size and weight categories, thus resulting in a “bus centric” approach, rather than a “user centric” approach. A user centric approach would provide an emerging spacecraft with only the resources that it requires for its mission; for example, only battery power, or communication capability, or various other control capabilities, rather than the full panoply of functions and capabilities provided by a traditional spacecraft bus. Such a cost effective approach would reduce the overall cost of each emerging spacecraft that is to be carried into space on a launch vehicle because the spacecraft would only be provided with limited resources suited to its particular mission. Such an approach would also enhance overall system integrity because the emerging spacecraft would not be required to access the traditional spacecraft bus or the primary payload(s) on the launch vehicle to meet its operational requirements. This would reduce the points of potential failure for the traditional spacecraft bus and be completely non-invasive to the traditional spacecraft bus. Physical separation of the emerging spacecraft from the traditional spacecraft bus would further increase the reliability and competence of launch vehicle operation, the primary payload mission and all secondary payload missions.